The present invention relates to conveying apparatus, and more particularly to a novel apparatus for conveying large, relatively flimsy sheets of material such as veneer or the like.
In the production of veneer, it is conventional, after peeling, to transfer the veneer through a dryer. A dryer includes a source of heat and suitable air moving equipment for moving warm air across the surfaces of the veneer to effect drying. One form of conveying apparatus for transferring veneer sheets through a dryer is the so-called "wicket" conveyor. Such a conveyor usually includes a pair of laterally opposed endless chains each of which is trained around opposed sprockets. A drive shaft connects the sprockets and is operable for moving the conveyor through arcuate and rectilinear runs. Mounted on top of the chains or suitably connected thereto are a series of elongate arms or "wickets" which are aligned in the direction of conveyance. As a wicket moves through the arcuate run, suitable infeed mechanism transfers a veneer sheet onto the top surface of the wicket and is carried therealong and through the upper rectilinear run which extends through the dryer. After a predetermined period of time, the sheet is transferred through the downstream arcuate run and is discharged onto an offbearing conveyor or the like.
A typical example of a so-called "wicket" construction used for the transfer of sheets is described in Seedorf, U.S. Pat. No. 3,276,569. The sheet handling mechanism disclosed in that patent includes wicket assemblies wherein each wicket is mounted on a mounting base to define an inclined plane for holding a sheet. A pair of fingers are mounted on the wicket above the base to define a pair of sheet edge supports. Each of the wicket assemblies includes a pair of members which are spaced-apart in a direction transverse to the direction of conveyance in order to provide sufficient support for holding a sheet. As the wicket assemblies move through an arcuate run to a horizontal run, they repose, in an inclined manner, one on top of another to hold the sheets.
Another conventional type of conveyor assembly using "wickets" is disclosed in Weber, U.S. Pat. No. 3,605,992. Also exemplary of known conveyors for transporting sheets is Russell, U.S. Pat. No. 2,821,286. Russell discloses a wicket construction in which each wicket assembly inclines relative to one another during the horizontal run through a dryer or oven. All of the references described thus far contemplate that the wicket assemblies will incline, one relative to another, so that sheet material will be permitted to bear against the inclined wicket.
A problem residing in conventional wicket-type conveyors resides in the fact that large, heavy wickets may be necessary to transport relatively large and thin sheets of veneer. Veneer sheets having a width in the range of 54 inches and lengths to 8 feet and above are heavy and unwieldy. When such sheets are loaded onto a wicket, as the wicket is being transferred through the arcuate run, the weight of the sheet will tend to bend the wicket downwardly so that the wicket will not properly catch and move the sheet upwardly for transferring it through the rectilinear run. It can be appreciated that a wicket, while it is being transferred through the arcuate run, is supported in cantilever manner by the conveyor. Thus, in those applications requiring long wickets, in order to accomodate reception of wide sheets of veneer, there is considerable bending stress placed upon the wicket.
With the above problem in mind, it is accordingly an object of the present invention to provide a novel wicket-type conveyor in which each of the "wickets", hereinafter referred to as arm means, is structurally enhanced so that during the arcuate run each will readily support a wide sheet of veneer. To this end, the present invention contemplates that each arm means is constructed as a pair of elongate members, which flex outwardly, one relative to the other, during movement of the arm means through the arcuate run. By "flexing" it is meant that the elongate members will bend or arc outwardly, relative to the longitudinal axis of the arm means so that a rigidified structure is provided. This rigidified structure, caused by the flexing action, will result in greater support for receiving a infed sheet during the arcuate run.
Additionally, it is an object of the present invention to provide an interconnected array of substantially similar arm means, pairs of which will spread apart for receiving an infed sheet during the arcuate run and which will return to an unflexed configuration for holding a sheet during the rectilinear run. In the unflexed configuration, adjacent pairs of arm means will hold a sheet in a substantially vertical position during the rectilinear run.
Still another object of the present invention is to provide an array of interconnected arm means, each of which includes a pair of elongate members spaced-apart from one another and connected adjacent their outer ends. Conversely, the ends of the arm means which are secured to the conveyor angulate, one relative to the other, during the arcuate run so as to flex the elongate members outwardly relative to one another. The flexing action is created because the outer ends of the elongate members of each arm means are connected to one another.
These and additional objects and advantages of the present invention will be more readily appreciated from a consideration of the drawings and the detailed description of the preferred embodiment.